Refrigeration



Feb. 3, 1942. R. R. FlTzsiM'MoNs ETAL 2,271,547 n REFHIGERATION FiledMaron 4, 1940 n s m. m n N .Q a. mm .|l lu m .MB m m5 ,l |1 5, IHM...NM1 m wm W. HV1 .hulu JHW|||||M d ,111mm .VM e NM ||u|||| -||H .MIIIIII UIHIH i f lll III- R h -l. HW QN wu ma m lm, n .Q n UP -w- H. 5Nm NNE y Patented Fens, 1942 UNITED STATES PATENT OFFICE REFRIGERATIONRichard R.. Fitzsimmons, Chicago, and George A. Brace, Winnetka, Ill.,assignors to The Hoover Company, North Canton, Ohio 22 Claims.

This invention relates to the art of refrigera- `tion and moreparticularly toan improvement in three-:duid absorption refrigeratingsystems of the type utilizing a power operated device for circulatingthe fluid mediums normally contained in such apparatuses. The rotatingpart of the power operated circulating device is supported in alubricant and a seal is provided between the rotating element and theother portions of the refrigerating apparatus which will prevent escapeof lubricant therefrom.

It has been found very advantageous to cirenvironment. It is alsoimportant in systems of this type to energize the heater for theabsorption refrigerating machine and the motor for the fluid circulatorin proper sequence which depends upon various factors described indetail herein-V culate the fluids in refrigerating systems of theabsorption' type by means of a small power operated mechanism,preferably a small electric motor operated centrifugal fan.Refrigerating systems of this type operate under .extremely highpressures wherefore it 'is necessary to weld or otherwise securely sealallelements'of the ap'- paratus into a unitary whole. Consequently, ithas been found most advantageous to utilize a small induction type motorwith the rotating element thereof sealed within the system andspecifically within a thin walled motor shell around the outside ofwhich is mounted the field windings. Due to the fact that these systemsoperate under extremely high pressure and are customvarily weldedtogether, field servicing is impossible and it is likewise impossible tolubricate' the motor after the initial construction of the apparatuswithout disassembling the system. In order to solve the lubricationproblem the motor rotor shell is preferably lled with a lubricatingmedium which may be either solid or fluid at atmospheric temperatures.This arrangement provides adequate lubrication for the motor but thepressure in systems of this type varies widely between the on and offcycle, wherefore the lubricant may become charged with refrigerant atthe high pressure prevailing during an 0n cycle. When the apparatusbecomes inoperative and the system pressure drops, the refrigerant whichhas found its way into the lubricant, then tends to boil off or causefoaming which removes the lubricant from the motor shell and distributesthe same to other parts of the systemI in which it cannot perform alubricating function and also in which it may interfere with properoperation of'the system.

Another factor of appreciable importance in this connection results'fromthe fact that the apparatus may be up-ended or placed on its. sideduring sh'pment and handling procedures whereby fluid lubricant con-Accordingly, it is a principal object of the present invention toprovide an absorption refrigerating system of the type including a poweroperated fluid circulator which is so constructed and arranged as toovercome the difficulties mentionedv above.

More specifically it is an object of the present invention to provide anabsorption refrigerating system of the three-fluid type utilizing .apower operated fluid ci'rculator in which the rotating part of the powerunit is supported in a lubricant which may be fluid or solid undernon-operating conditions.

It is a further object pf the invention to provide a sealing arrangementfor a power unit of the typementi-oned above which will prevent thelubricant from spilling from the power unit housing during handling;which will prevent discharge of the lubricant from the motor shell byfoaming or boiling out of refrigerant vapor during the off cycle of theapparatus; which will maintain a hermetic seal between the power unithousing and theremaining portions of the refrigerating system' until thepressures in the motor and inthe system are substantially balanced;which will vrelieve the power circulating unit of the objectionablefriction load of a running seal during the operative period of theapparatus; and which may be utilized in a proper arrangement of parts toeffect a desired control of the refrigerating mechanism.

It is a further object of the present invention to provide a three-fluidabsorption refrlgerating apparatus having .a power operated circulatingYunit with the rotating part of the power unit at least partiallysubmerged in a lubricant and separated from the balance of the apparatusby a seal which is arranged to be maintained in tightly sealed conditionas long as there is an appreciable pressure diiferentialexisting betweenthe power unit housing and the remaining part of i the refrigeratingsystem and also serves toL block installation or other n tained withinthe motor shell will spill therefrom rotation of 4the motor as long assuch pressure differential prevails.

It is a further object of the present invention to provide an absorptionrefrigerating system Power unit seal which is maintained in sealedcondition during the oir cycle of the apparatus and which is moved tothe open condition as an incident of energization of the system.

It is another object of the present invention to provide an absorptionrefrigerating apparatus including a power unit provided with a rotatingelement which is submerged in a lubricant nonfluid at ordinarytemperatures and which is so correlated to the control mechanism of thesystem that the lubricant will act to prevent operation of thecirculator prior to the time at which refrigerant vapor has beenproduced in the boiler and supplied to other portions of therefrigerating mechanism.

Other objects and advantages of the invention will become apparent asthe description proceeds when taken in connection with the accompanyingdrawing in which:

Figure 1 is a diagrammatic representation of an absorption refrigeratingapparatus with the motor and control of this invention applied thereto;

Figure 2 is a sectional view of the power unit according to thisinvention; and

Figure 3 is a view depicting the relation of the parts of. the movableseal with the seal in open position.

Referring to Figure l of the drawing, there is disclosed a three-fluidabsorption refrigerating system comprising a boiler B, an analyzer D, anair-cooled rectifier R, a tubular air-cooled condenser C, an evaporatorE, a gas heat exchanger Gr, a tubular air-cooled absorber A, a solutionreservoir S, a liquid heat exchanger L, and a circulating fan F which isdriven by an electric motor M.

The above described elements 'are interconnected by various conduits toform a plurality of gas and liquid circuits constituting a completerefrigeration system to be described in more detail hereinafter.

The refrigerating system will be charged with a suitable refrigerant,such as ammonia, a suitable solvent such as water, and a suitablepressure equalizing medium such as nitrogen.

The boiler B will be heated in a suitable manner as by an electricalheater or a gas burner I as may be desired. 4

The application of heat to the boiler Bliberates the refrigerant vaporfrom the strong solution contained therein. The vapor so liberated rpasses upwardly through the analyzer D in countertlow relationship tostrong solution flowing downwardly through the analyzer. Furtherrefrigerant vapor is generated inthe analyzer by the heat ofcondensation of absorption solution, vaporized in the boiler andcondensedV in the analyzer. The refrigerant vapor ,is conducted from theupper portion of the analyzer D to the upper portion of the condenser Cthrough a conduit i3 which includes the air-cooled rectifier R- whereinany vapor of absorption solution passing through the analyzer iscondensed and returned to the analyzer through the conduit I3.

The refrigerant vapor is liquefied in the con'l denser by heat exchangerelation with atmospheric air and is discharged from the bottom portionthereof through a, conduit I5 into a downnwardly extending conduit I6.The bottom portion of conduit I6 connects to the bottom portion of anupwardly extending conduit Il through a U bend I8. The conduit I6 isappreciably longer than the conduit I1 for a purpose to be describedlater. Conduit I1 opens at its upper end into a conduit which dischargesinto the evaporator in a manner to be described in more detailhereinafter.

The weak solution formed in the boiler by the generation of refrigerantvapor therefrom is conveyed from the boiler through a conduit 2l, theouter pass of liquid heat exchanger L through a precooler 22 and conduit23 into the solution reservoir S. The weak solution is conveyed from thesolution reservoir S through a U-shaped conduit 24 opening into anupwardly extending tube 25 of small diameter, forming a gas lift pumpwhich discharges into the top of the absorber A. It is evident that thetop of the absorber is appreciably above the solution level normallyprevailing in the boiler-analyzer-reservoir system whereby some meansmust be provided to elevate the absorption solution to the top of theabsorber A. For this purpose, a small bleed conduit 21 is connected tothe discharge conduit 28 of the circulating fan F and leads to thejunction of the conduits 2l and 25, which is below the solution levelnormally prevailing in the reservoir whereby the weak solution iselevated to the top of the absorber by gas lift action.

In the absorber the Weak solution flows downwardly by gravity incounterflow to the rich pressure equalizing medium refrigerant vapormixture flowing upwardly therethrough. The refrigerant vapor content ofthe mixture is absorbed into the absorption solution and the heat ofabsorption is rejected to the surrounding air by air cooling fins whichare mounted on the exterior walls of the absorber conduit. The strongsolution formed in the absorber discharges into the conduit 32 whichopens into the inner pass of the liquid heat exchanger L. From the innerpass of liquid heat exchanger L, thel strong solution is conveyed to theupper portion of the analyzer D by conduit 33 whereby it flowsdownwardly through the analyzer in counterflow to the rising vaporsgenerated in the boiler.

The weak pressure equalizing medium refrigerant vapor mixture present inthe absorber A is taken from the upper portion thereof through the yconduit 35 into the suction side of the circulating fan F in which it isplaced under pressure and discharged through conduit 28 into the outerpass of the gas heat exchanger G and therefrom through a downwardlyextending conduit 3B into the bottom of the evaporator E.

The conduit 20 opens into the bottom of the conduit 36 whereby theliquidrefrigerant supplied to the evaporatorr -enters simultaneously withpressure equalizing medium which is placed under pressure by thecirculating fan F. The

diameter of the conduit of the evaporator is relatively small wherebythepressure equalizing medium flows through it at a' relatively highvelocity. The rapidly flowing pressure equalizing medium sweeps or dragsthe liquid refrigerant through the evaporator coil as the refrigerant isdiffusing into the pressure equalizing medium to produce refrigeration.In the box cooling portion 40 of the evaporator, the velocity of thepressure equalizing medium is slow by reason of the large diameter ofthat portion and 'any remain ing liquid refrigerant flows therethroughby gravity as it is evaporating into the pressure equalizing medium. Anyliquid refrigerant not evaporated in the evaporator iiows by conduit 45,the inner pass of gas heat exchanger G and conduit 46 to the bottom ofthe absorber A so as not to itnterfere with the operation of the motorfan uni The rich pressure equalizing medium refrigerant vapor mixtureformed in the evaporator is conducted therefrom into the inner pass ofthe gas heat exchanger G througha conduit 45. The opposite end of thegas heat exchanger G communicates with the bottom portion of 'absorber Athrough a conduit 46. In the absorber A the rich pressure equalizingmedium refrigerant vapor mixture flows upwardly in counterflow toabsorption solution whereby the refrigerant vapor content ofthe mixturei's absorbed` bythe weak solution.

The bottom coil of the evaporator E is provided with a drain conduit 43which opens into the solution discharge conduit 32. Conduit 48 opensinto the top portion of the bottom coil of the evaporator whereby itwill not completely drain suchconduit. The upper portion of dischargeconduit I5 of the condenseris vented through avent conduit 49 into theinner pass of the gas heat exchanger G. f The solution reservoir isvented through a conduit 50 into the suction conduit 35 of thecirculating fan.

' Tightly pressed overlthe exterior of the shell 52, opposite the rotor53, is a field stack 62 provided with field coils63.

The interior of the fan casing 5I is separated into a suctionchamber,and a pressure chamber by a plate 9`I having an opening .92leading to V the suction 'or eye side of the fan.

A thermostatic bulb 63 is positioned in contact with the lower coil ofthe evaporator Evand 10 is connected to a control device 64 of convenl5structionby tube 68.

The circulating fan F places they pressure'- equalizing medium.discharged therefrom under a small pressure in the neighborhood of a-pressure of 41/2 inchesof water over that prevailing in the suctionside I the fan. In order to prevent this pressure which also prevails inthev conduit 36 from being carried b ack through the lcondenserdischarge conduitythe condenser and conduit I3 to the analyzer,4 theconduit I6 is made appreciably longer than the conduit I1` ywhereby apressure balancing column of liquid is formed in the conduit I6 whichextends above the point of connection between the conduits I1 and 20, adistance sufficient to overcome the pressure produced by the circulatingfan in the conduit 36.

The motor fan unit comprises a fan casing I and a cylindrical shell 52forming a housing for the 'fan F and vthe motor rotor 53. The motorrotor 53 is rigidly connected to the fan F by a shaftv 59 which issuitably supported for rotation by bearing 'assemblies 54 and 55. 'Thelower bearing assembly 54 comprises a two-part tungtional constructionby tube 65. A second thermostatic bulb 66 is positioned in contact withthe tube I3 adjacent. rectifier R and is connected to a second controldevice 61 of conventional con- The thermostatic bulbs 63 and 66 andthetubes65, 68 are filled with a volatile fluid. ina well known manner sothat the expansion and contraction of the fluid willI operate thecontrol devices 64 and 61.` v n I One side of the controldevice. 64 isconnected to one side of the power line by a conductor 69 and itsoppositeside is connected to a magnetically operated gas valve lbyconductor 1I, the opposite side o f which is connected to the other sideof the power line .by conductor 12'.

Conductors 1I and 12 are connected respectively by conductors 13 and 14to the opposite sidesbf the field coil 83. One side of control device 61is connected to the conductor 69`by conductor 15 and its opposite sideis connected to conductor I 13 by conductor 16. A manual switch 11 isplacedin the conductor 13 betweenits point` of yconnection to theconductors 16 and 1I'.

A low ilame by-passf 69` by-passes the magsten carbide thrust bearing 56anda large clearance Babbitt radial bearing 51. The upper bearingassembly also includes a large clearance, A

radial Babbitt bearing 58 and a seat 60 to co` operate with a movableseal or valve member 6I mounted for sliding movements on the shaft 59.

The member 6I is secured to the shaft 59 by means of a flexible metallicor synthetic4 rubberv diaphragm 62 `which is bonded at its outervgreater than the diameter of that portion .of the diaphragm 6 2 whichis rigidly secured to the netically operated gas valve 10 to' supply aminimum flame `to the burner. II). The minimum flame may beiregulated'bya valve 96 in the minimum flame by-pass 89. The valve 90 may beregulated to supplv a minimum flame to the burner I0 ofsuch value as toact as merely a pilot or lighter flame for the burner or it may beregulated to supply sufficient heat to the boiler to maintain it atsubstantially operating tem-l perature during idle periods.

The shell 52 of the motoris filled with a lubricant to the level shownwhich lubricant may be fluid at all times or it may be solid at ordinarytemperatures and fluid at the operating temperature ofthe motor. Onesuch lubricant is paraln which may be had in a wide range of meltingpoints and specific gravity. .By mixing paraffin with other lubricantsalmost any melting point desired may be obtained.

5 The member 6I is made of. magnetic material so that when the fieldcoil 83 is energized, the maghnetic'flux leakage from the end of thefield stack 82 to the ,rotor 53 will exert a force thereon tending topull the valve or seal 6I downwardly. The strength of the spring 19should be so seg lected that it will exert a Vforce sufficient toovercome the weight of themember 6I and the resistance of the diaphragm62` by a small am-ount so that when the motor is de-energized, the valve6I will be held lagainst its seat 60.

shaft 59 by nut 80 for a purpose to be hereafter described.

standing annular rim 85 which extends Slightly a throw-off ring 66 whichrotates with the shaft 59.

When absorption refrigerating apparatus of the type under considerationstands idle for long periods of time, for instance ina degree' room theinternal pressure goes down to. approximate- 70 ly 2'10 pounds persquareinch. When the appara The bearing assembly 55 also includes an uptus isiii operation, the pressure rises to approximately 325 to 345 pounds per'square inch, -depending upon the operating conditions, such as vtheambient temperature and the amount of energy supplied to the boilerduring idle periods.

In absorption refrigerating apparatus of the type using a pressureequalizing medium, the pressures throughout all parts of the system aresubstantially equalized during operation and therefore only a smallpcwer unit Yis required for circulating the mediums in their circuits.Since the force exerted on the valve or seal 6|4 by the magnetic iluxleakage of such small power unit` would of necessity be small. the valveor seal' 6| is so made as to be positively opened as the pressure buildsup within the apparatus. l

Figure 3 shows the relative positions of the parts of the seal or valveIl so as to illustrate how this is accomplished. The inner diameter ofthe seat 6l is shown as greater than the exterior diameter of the nut Iwhich attachesthe diaphragm 62 to the shaft 59. Now if a pressure isbuilt up on the interior of the seal Si including the space between thediaphragm 62 and the seal this pressure will exert an equal force in alldirections. Since the nut l0 is rigid with the shaft i! and thereforeimmovable, the pressure exerted on this area will have no effect,tending to move the diaphragm I2 or the member tl. However, since thearea under pressure in a downward direction is greater than that in anupward direction there will be an unbalanced force tending to move theseal il downwardly due to the reaction thereon by the force exerted onthe unsupported portion of thediaphragm 62. Immediately the seal isbroken, the .pressures will be equalized on opposite sides of the sealbut since the seal or valve only moves a few thousandths of an inch, itwill contact the rotor 5I and be held against it in opposition to thespring 1l by magnetic flux leakage so long as the iield coil Il remainsenergized. When the eld coil is de-energized the spring 19 willimmediately close the seal.

In order to protect the diaphragm 61 against the pressure inside theshell 52 over that in the Jfan chamber 5I, when the machine remains idlefor long periods, the seal or valve member il is extended inwardly asshown in 1l so as to leave a slight space between it and thenut Il. Thusthe area of the unsupported portion of the dia- 5i multiplied bytheannular area formed by the external diameters of the nut Ill and thevalve 6| itself.

Now as the pressure in the system goes down a considerable force will beexerted, forcing the valve 6| against its seat 60, which will operate topositively block the rotor against rotation until the pressures onopposite sides of the valve become substantially equalized.

If the shell 52 is filled with a lubricant, solid at ordinarytemperatures and fluid at the operating temperature of the motor, thevalve 90 will be set to supply a minimum or pilot flame to the burnerI0. The switch 11 will then be closed. When the control B4 calls forrefrigeration, the motor and the valve 10 will be simultaneouslyenergized. It will take some time for the boiler to heat upsufiiciently'to supply refrigerant vapor to the condenser but since therotor 53 is blocked by the solid lubricant, the motor will not operateuntil the lubricant has melted. The

melting point of the lubricant should be selected phragm against upwardpressure is very small As soon as the system is de-energized, the valvey il will be seated against its seat l. Now as the system cools oil. thepressure in the fan casing n Il will go down, but since the valve Si isclosed, the pressure in the shell 52 will be maintained.

Referring to Figure 2. the reactions on member 0l will then be asfollows: The pressure in the shell I2 will act in an upward direction onan annular area formed by the external diameters of the ange Il and thenut Il and in a downward direction on an annular area formed by theexternal diameters of flange u and the valve il itself. The latter areais obviously less than the former and the forces exerted on the smallerarea will be balanced.

Ihe pressure in the casing 5I will act in a downward direction on anannular area formed by the external diameters of the nut 8O and thevalve il itself. Since the pressure on this latter area in anl upwarddirection is greater than in a downward direction, the total unbalancedforce tendingtofseat Ithe valve il, will be the difference yin pressuresin the shell 52 and the casin! relative to the heating effect of themotor field and the heating rate of the boiler so that the lubricantwill be melted by. the time refrigerant vapor is being supplied to thecondenser. By this time the pressures on opposite sides of the diaphragm62 will have become equalized and the seal il will be held against therotor by the magnetic flux leakage.' This will result in a condition inwhich the motor begins operation' at the same time liquid refrigerant isbeing supplied to the evaporator E and the seal BI will be free of theseat B0 so that no frictional drag by the seal will be applied to therotor il.

If the strength of coil I3 is not sufficient to move the seal ildownwardly, the pressure in the fan chamber 5I will continue to build upabove that in the shell 52 and force the member tl downwardly asexplained above.

When the control Il operates to de-energize the burner and motor. thevalve or seal il will immediately close due to the action of the spring19. As the pressure in the system is slowly reduced, below that in theshell 52,-the member 6I is pressed forcibly against the seat Gl asexplained above, thus assuring that the pressure in the shell 52 will bemaintained and therefore no refrigerant vapor will boil out of the oilin the shell 52 and that the original charge of oil in the shell will beretained therein for indefinite periods.

Since the motor is never energized during shipment or other handlingoperations, the valve or seal il will remain closed during such timesand the oil in the shell 52 cannot escape therefrom. The liquid mediumsin other parts of the apparatus cannot get into the shellv52 to dilutethe oil therein. Any liquid medium that may collect in the fan chamber5| will be thrown of! by the ring l0, immediately the motor beginsoperation and be drained away through conduits 21 and 2l to the solutioncircuit so that it cannot enter the shell 52 when the valve or seal ilis opened. If the shell 52 is filled with a lubricant which is fluid atall times and the valve QI is set to deliver a minimum or pilot ame tothe burner il, the switch 11 should be open. When the control il callsfor refrigeration, the valve 1l will be energized to supply a maximumilame to the burner Il for operating conditions but`since.the switch 11is open the `motorl will not be energized. The (burner Il will continueto supply heat to the boiler and eventually hot refrigerant vapors willpass through the rectiytime thereafter and will still fier R and expandthe fluid in the bulb 55 and operate the control 61'to energize thefleldcoil 83. By this time the pressure in the fan chamber I will have becomeequalized with that in the shell 52 and the valve or seal 6| will beopened as soon as the motor is energized. At the same time liquidrefrigerant will be supplied to the evaporator E so that the circulationof the mediums' will be delayed until liquid refrigerant is beingsupplied to the evaporator.

It is to be pointed out that even if the switch 11 is left closed themotor cannot begin operation until the pressures on opposite sides ofthe seal 5l are equalized since the pressure of the seal 6I against theseat 60 will operate to block the rotor as explained above. The onlyresult would be a slight wasting oi the electrical energy supplied tothe motor while the boiler is heating up,

The delay of the operation of the motor until refrigerant is beingsupplied to the evaporator is important since circulation of the medi--ums priorto that time would decrease the efiiciency of the apparatus.The circulation of the cold solution from the absorber to the boilerwould have the effect of cooling the boiler and thus extending the timeit the boiler to an operating temperature since this cold solution wouldalso have to be heated. The circulation of weak, warm solution from theboiler to the absorber would also have the effeet of heating theabsorber and thus throwing additional heat load thereon which must bedissipated before the absorber can eiciently ab-.

sorb refrigerant vapor from the inert medium refrigerant vapor mixturecirculating therethrough. Since the inert medium being circulated atthis time contains little refrigerant vapor to be absorbed, the solutionleaving the absorber and returning to the boiler will be comparativelyweak which will result in a further decreaseA in the efficiency of theapparatus.

If warm inert medium is circulated from the absorber to the evaporatorbefore liquid refrigerant is being supplied to the evaporator this warmgas acts to heat the evaporator before any liquid refrigerant isproduced to cool it b y the evaporation of the refrigerant. Theapparatus would thus operate to pump heat from the boiler to theevaporator and further reduce the efficiency of the apparatus.

With the switch 11 open as described above, when the control 64 operatesto de-energize the burner I0, the boiler will remain hot for somevaporto the condenser. The motor, however, is still energized and willcontinue to circulate the mediums until the rectifier cools sufficientlyfor the fluid in the bulb 65 to contract and operate the control 51 tode-energize the motor. This is also important since the liquidrefrigerant supplied to the evaporator during the cooling off period ofthe boiler would otherwise be wasted.

When the motor is de-energized the valve or seal 6I will -immediatelyclose and prevent boiling off of vapor from the oil in the shell 52 andconsequently the original charge of oil will -be retained in Lhe shell.

If the valve 90 is set to supply suflicient heat to the boiler tomaintain it at substantially the operating temperature during idleperiods, the switch 11 should be closed so that the control 54 willsimultaneously energize the valve and the 4 motor.

Since under the above conditions, the boiler would take to bringl supplyrefrigerant is at substantially operating temperature, it is ready tosupply refrigerant vapor to the condenser immediately the valve 10 isopened to apply a maximum pressures on opposite sides of the seal 6lwill also be substantially equalized so that the motor is ready foroperation to circulate the mediums in the apparatus coincidentally withthe supply of liquid refrigerant to the evaporator.

'The valve or seal 5l could be rigidly attached to fthe shaft 59, thethrust bearing 56 mounted on a spring so as to press the valve or sealagainst the seat 60 with the rotor positioned slightly above the fieldstack 82 so that when the coil 83 is energized, the whole rotor will bepulled downwardly against theaction of the spring so as to open thevalve `or seal 5| when the motor is energized. This modification wouldhave the advantage that a stronger pull would be exerted to open theseal than in themodiflcation of Figure 2. It has also the advantage thatif a solid lubricant is used, the valve could not be opened until thelubricant is melted so that the motorI vhigher pressure in the shell 52would not act to forcibly press the valve against its seat. when alubricant is used times, the switch 11 should be maintained in openposition to assure that the valve would not be opened until thepressures on opposite sides thereof had become equalized, as explainedabove.

By supporting the rotor 53 in a liquid medium such as lubricant, therotor centers itself as it reaches itsoperating speed. This isdue to thefact that if the rotor is off-center at the beginning of its operation,the liquid will tend to rotate with the rotor and be drawn between therotor 53 and the shell 52 at the point where the rotor is closest'to theshell and move the rotor away from the shell at that point. This actionwill continue until the rotor is completely centralized. It is to benoted that the space between the rotor and shell when the rotor iscentralized is very small and may be only a few thousandths of an inch.

The fact that the action of the lubricant automatically centers therotor renders it possible to make the radial Babbitt bearings 51 and 58with a much larger clearance between their bearing surfaces and that ofthe shaft 59 than would otherwise be possible. Thus the bearing surfacesare only in contact when the rotor is starting and the wear thereon willbe negligible.

The buoyant effect of the lubricant will also lighten the load on thethrust bearing 56 and thereby reduce the wear thereon. As the radialbearings are out of contact with the shaft during operation a muchquieter motor will result.

From the foregoing it can be seen that this invention provides anabsorption refrigerating apparatus of the pressure equalized type,utilizing a power unit for circulating the mediums, in which a seal isprovided between the power unit rotor and fan whereby the lubricant inthe rotor shell cannot escape into other parts ofthe apparatus, eitherduring operation or during shipment or other handling operations, inwhich the liquid mediums in the apparatus cannot enter the rotor shellto which the operation of the power unit is delayed until liquidrefrigerant is belng'supplied to the Thus flame to the burner I0. The

which is fluid at alldilute the lubricant therein, in

evaporator and in which the operation of the power unit is continuedafter the boiler is deenergized so that the mediums will be circulatedso long as liquid refrigerant is being supplied to the evaporator.

While we have shown but one embodiment of our invention, it is tobeunderstood that this embodiment is to be taken as illustrative onlyand not in a limiting sense. We do not wish to be limited to thespecific structure shown and described but to include all equivalentvariations thereof except as limited by the scope of the claims.

We claim:

1. An absorption refrigerating apparatus ofthe type having higheroperating pressures than that prevailing therein during idle periodscomprising a boiler, power operated means for circulating the mediums inthe apparatus, said power means including a motor rotor separated fromthe remainder of the apparatus by a partition having a valved opening,means for simultaneously energizing the boiler and power means, andmeans for holding the valve in closed position until the pressures onopposite sides thereof have equalized.

2. An absorption refrigerating apparatus having a higher operatingpressure than that prevailing in the apparatus during idle periodscomprising a heater for the boiler, and power operated means forcirculating the mediums in the apparatus, said power means comprising amotor fan unit in which the motor rotor and fan are separated by apartition having an opening, movable seal means mounted on said rotorand cooperating with a seat surrounding said opening for closing saidopening, means responsive to a diierence in pressure on opposite sidesof said opening forholding the seal against its seat, means forenergizing the heater, and means responsive to a condition incident tothe energization of the heater for energizing the motor an moving theseal away from its seat.

3. An absorption refrigerating apparatus having high internal pressuresduring operation and lowl internal pressures during idle periods, incombination with a heater for the boiler and a motor fan unit iorcirculating the mediums in the apparatus, said motor fan unit comprisinga vertical casing having a sealable opening between the motor rotor andfan and said rotor being submerged in a lubricant, means for energizingsaid heater, and means responsive to a condition incident totheenergization of the heater for opening the sealable opening.

4. An absorption refrigerating apparatus having high internal pressuresduring operation and low internal pressures during idle periods, incombination with a heaterfor the boiler and a motor i'an unit forcirculating the mediums in the apparatus, said motor fan unit comprisinga vertical casing having a sealable opening between the motor rotor andfan and said rotor being in contact with a lubricant, means forenergizing said heater, and means responsive to a condition incident tothe energization of the heater for energizing the motor and opening thesealable opening.

5. An absorption refrigerating apparatus comprising a motor fan unit forcirculating the mediums in the apparatus, said motor fan unit includinga casing having a sealable opening between the motor rotor and fan,means for energizing the apparatus, and means responsive'to a conditionincident to the energization of the apparatus for opening said sealableopening.

6. An absorption refrigerating apparatus of the type havingpressurevariations between running and idle periods comprising a boiler, powermeans for circulating the mediums in the apparatus, said power meansincluding a motor rotor separated from the remainder of the apparatus bya partition having a valved opening, means for simultaneously energizingthe boiler and power means and means selectively actuatable to energizethe boiler prior to the energization of the power means and means forholding the valve in closed position until the pressures on oppositesides thereof have equalized.

7. An absorption refrigerating apparatus comprising a -circuit forliquid mediums, a motor fan unit for circulating 'said mediums, saidmotor fan unit comprising a casing having a sealable opening between themotor rotor and fan and being normally positioned in that part of thecircuit inaccessible to liquid mediums but subject to being flooded withliquid medium during shipment or other handling operations, and meansresponsive to the energization of the apparatus for opening saidsealable opening.

8. An absorption refrigerating apparatus comprising a circuit for liquidmediums, a motor fan unit for circulating `the liquid mediums in itscircuit, comprising a vertically positioned motor fan housing with thefan chamber positioned above the motor rotor and being positioned inthat part of the circuit normally inaccessible to the liquid mediums butsubject to being iiooded during shipment or other handling operations,said motor rotor being submerged in part in a lubricant and a sealbetween the motor rotor and fan, and means responsive to theenergization of the apparatus for opening said seal whereby said sealcloses the motor rotor casing from the other parts of the apparatusduring idle periods and is open during running periods.

9. An absorption refrigerating apparatus of the type subject to internalpressure variations between operating and idle periods in combinationwith a motor fan unit for circulating the mediums in the apparatus,means responsive to said pressure variations for blocking the rotor andbeing so constructed as to release the rotor when the internal pressurereaches a pre-determined value.

10. The method of operating absorption refrigerating apparatus of thetype using a motor fan unit for circulating the mediums in the apparatuscomprising energizing the apparatus, blocking the motor rotor againstoperation and 'utilizing a condition of the mediums within the systemresulting from the energization of the'apparatus for releasing themotor'rotor.

l1. The method of controlling the operation of an absorptionrefrigerating apparatus of the type using power means for circulatingthe mediums in the apparatus comprising energizing the apparatusincluding said power means, delaying the operation of the power meansand utilizing the.

rising pressure incident to the energization oi 'the apparatus forterminating the period of delay in the operation of the power means.

12. An absorption refrigerating apparatus Icornprising circuits for aliquid and gaseous medium inthe apparatus, a motor fan unitvforcirculating said mediums, said motor fan unit being positioned in thatpart oi.' the circuit inaccessible to liquid mediums during normaloperation, but subject to being flooded by liquid medium during shipmentor other handling operations and comprising an upper Ian housing andlower rotor shell separated by a partition having a valved opening,for'housing the fan and motor rotor, and means responsive to theenergization of the motor for opening the valve opening.

13. An absorption refrigerating apparatus in which the total pressureWithin-the system rises during operation over that prevailing in theapparatus during idle periods, in combination with power means forcirculating the mediums in the apparatus, said power means comprising acasing for housing a motor rotor and fan with an opening therebetween, avalve for closing the opening, means responsive tothe energization ofthe lmotor tending toopen the valve and means responsive tov adiiference in pressure between the motor and fan casing for opposingsaid rst mentioned means whereby the `valve remains closed until thepressures are equalized on `opposite sides thereof.

' 14. An absorption refrigerating apparatus in which the total pressureswithin the apparatus riseduring operation over that which prevails inthe apparatusy during idle periodspin combination with a motor fan unitfor circulating the mediums in-the apparatus, said motor fan unitcomprising a motor fan casing with a movable seal between the motorrotor and fan, means responsive to the' de-energization f the motor forclosing said seal, means responsive to a reduction in pressure in thefan chamber for blocking the rotor until the pressures on opposite sidesof the seal are equalized, and means responsive to the energization ofthe rotor for opening said seal after the pressures on opposite sidesthereof have equalized.

15. An absorption refrigerating apparatus having high internal pressuresduring operation in combination -with a motor fan unit for circulatingthe mediums in the apparatus, said motor fan unit comprising a verticalcasing having a sealed opening between the motor rotor and fan,Qandmeans responsive to an equalization of pressures on opposite sidesof said opening for opening said seal.

16. An absorption refrigerating apparatus comprising a circuit for aliquid medium, a motor fan unit for circulating the liquid medium in itscircuit, comprising a vertically positioned motor `fan housing with thefan chamberpositioned above the motor rotor and being normallypositioned in that part of the circuit inaccessible to the liquidmediums but subject to being flooded during shipment or other handlingoperations, said motor rotor being at least partially submerged in alubricant and a seal between the motor rotor and fanl whereby the oilcannot get above `the motor rotor and being positioned lin that part ofthe circuit normally inaccessible to and lowintemal pressures' duringidle periods,

equalized, whereby the motor rotor is sealed from other parts of theapparatus until the pressure therein has reached that in the motor rotorcas'- ing.

18. An absorption refrigerating apparatus in combination with a motorfan unit for circulating the mediums in the apparatus, saidapparatusbeing subject to internal pressure variations between operatingand idle periods, said motor fan unit comprising a -vertical casing inwhich the fan is positioned above the motor rotor andthe lrotor iscontacted by a lubricant which absorbs the mediums in the apparatusunder pressure, and a sealable opening .between the motor rotor casingand the fan chamber which is closed during idle periods and open duringrunning periods, whereby the oil will be retained in the motor rotorcasing and not to be subject to the boiling oif of the mediums absorbedtherein when the pressure of the apparatus goes down during idleperiods.

19. Anr absorption refrigerating apparatus including a boi-ler incombination with a heater for the boiler and a motor fan unit forcirculating the mediums in the apparatus, said motor fanunit comprisinga casing having a sealable opening between the motor rotor and fan,means for energizing said heater, and means responsive to a conditionincident to the energization of the vwhich the motorrotor is submergedin a lubricant,'and a seal between the motoi` rotor and fan, said seal.being constructed to /open' when such a motor is energized and thepressure is equalized on opposite sides thereof.

21. An absorption refrigerating apparatus of the continuous typecomprising, a liquid container having an opening in its upper portion,lsaid opening forming the sole communication vbetween said container andthe remainder of the apparatus, a valve for closing said opening andmeans responsive to the energization of said apparatus for opening saidvalve and holding it open during the normal operation of said apparatuswhereby liquid will be retained in said container when .the apparatus isnot operating and there will be free communication between the containerand the remainder of the'apparatus when the apparatus is in operation.

- right position, said opening forming the sole comthe liquid mediumsand liable to being ilooded during shipment or other handlingoperations,

said motor rotor being supported in a lubricantv and a seal between themotor rotor and fan, and means responsive to a pressure difference onopposite sides of the seal for closing the seal and for opening the sealwhen said pressures are munication between 'said liquid containingportion and the remainder of the apparatus, means for closing saidopening andmeans responsive to the energization of said apparatus foractuating said closing'means to hold said closing means

